Hi Paul

This is a known issue with PDF viewers, not so much with Therion.

Have a look at https://therion.speleo.sk/wiki/contrib:externalviewers#viewers_for_therion_outputs_not_part_of_therion_package, particularly the bit about ‘transparency knockout’ and the examples lower down the page.

 

Just something to be aware you don’t have control over when you are drawing!

Bruce

 

From: Therion <therion-bounces@speleo.sk> On Behalf Of Paul Rowe
Sent: Friday, 21 June 2024 15:33
To: List for Therion users <therion@speleo.sk>
Subject: [Therion] Visibility of underlying objects in PDF viewers

 

Hi,

I'm mostly using the Sumatra PDF viewer to open my Therion PDF outputs as it doesn't lock the PDF file when it's open and you can then keep updating the map without closing / opening the PDF output each time.

 

However, I've noticed that Sumatra PDF doesn't seem to hide underlying objects in the final view, while some other PDF viewers like Acrobat do. Has anyone else noted this? I wasn't sure if it was a quirk in how the PDF is constructed by Therion or whether the issue is in Sumatra.

 

Example passage with 'area' of debris using "-place bottom", with overlapping closed circles of larger hand-sketched boulders using "-place top".

 

Sumatra view

Acrobat view:

 

I'm hoping this is something I can fix on the Therion side as end users of the PDF can end up with a map that's difficult to read if they're using some PDF viewers. The built-in PDF viewer in Firefox and Chrome has the same issue.

 

Cheers,

Paul

 

 

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